THE INTERPEDUNCULAR NUCLEUS IN VERTEBRATES: STUDY OF ITS ORIGIN AND DEVELOPMENT IN THE AVIAN EMBRYO

B. Lorente-Canovas, F. MarÍn, R. Corral-San Miguel, J.L. Ferran, L. Puelles, P. Aroca*
Dpt. of Human Anatomy and Psychobiology, School of Medicine, University of Murcia, CIBER de Enfermedades Raras (CIBERER), Instituto Universitario de Envejecimiento, Murcia, Spain.

The interpeduncular nucleus (IP) of vertebrates constitutes an important relay station within the descending pathways of the limbic system. It is a very complex and heterogeneous nucleus, expressing multiple neurotransmitters and displaying numerous afferences and efferences.

Pax7 and Nkx6.1 are two transcription factors expressed in the mature IP nucleus. These molecules are involved in the dorsoventral patterning of the hindbrain. Pax7 is expressed in the dorsal/alar plate, while Nkx6.1 appears in an intermediate ventral/basal plate position of the proliferative ventricular zone of the hindbrain.

We have studied the origin and development of the IP nucleus analyzing the spatio-temporal molecular expression of Pax7 and Nkx6.1. Our results indicate a dual alar-Pax7/basal-Nkx6.1 origin of the IP nucleus in the rostral hindbrain. Both transcription factors are thus markers of different and complementary territories in the IP complex. These results are corroborated by experimental analysis with quail-chick chimeras. Finally, we analyzed a possible correlation of the dorsal Pax7 or ventral Nkx6.1 subpopulations, with the respective neurotransmitter phenotypes. Funding: CIBERER V736, BFU2008-04156, Seneca 04548/GERM/06-10891 to L.P., BFU2006-C02-01 to P.A.